Coupling nut



FIG. 1 is a top, side, and front perspective view of a coupling nutshowing our new design;

FIG. 2 is a top, side, and rear perspective view thereof;

FIG. 3 is a top plain view thereof;

FIG. 4 is a right elevational view thereof;

FIG. 5 is a front end view thereof; and,

FIG. 6 is a rear end view thereof.

The broken lines represent portions of the structure that form no partof the claim.

The ornamental design for a coupling nut, as shown and described.